Breathing mask with oxygen reduced consumption

ABSTRACT

A breathing mask for aircraft crewmember comprising an on-demand regulator, said regulator comprising an inlet connected to a source of breathing gas and an outlet to exhaust the breathing gas, said outlet having an aperture controlled by a movable valve ( 18 ) having an open position when the crewmember breathes out and a closed position when the crewmember breathes in, wherein said breathing mask comprises latch means ( 30 ) operable by said crewmember to latch said valve in the open position, said latch means comprising an unlocking means ( 42, 46, 48 ) to release said valve when the cabin pressure is below a predetermined value.

FIELD OF THE INVENTION

The invention relates to the field of breathing mask for aircraft crewmembers and passengers.

BACKGROUND OF THE INVENTION

To ensure the safety of the passengers and crewmembers in case of adepressurization accident or the occurrence of smoke in the aircraft,aviation regulations require on board all airliners a safety oxygensupply circuit able to supply each passenger and crewmember with anoxygen flow rate which is function of the cabin altitude.

A mask and harness system is used to provide breathing oxygen. The masksystem has a face seal, a pneumatically-actuated harness, and aregulator to control the flow of oxygen. The regulator comprises aninlet connected to an oxygen source and an outlet to exhaust thebreathed gas outside. The outlet aperture is controlled by a movablevalve so that the valve is in an open position when the crewmemberbreathes out and is in a closed position when the crewmember breathesin.

The system is designed for a required five-second donning with one hand.

Such breathing mask is well-known in the art as an on-demand breathingmask. The demand regulators of these breathing masks are known from thedocuments FR 2,781,381 or FR 2,827,179 disclosing a pneumatic demandregulator, or from WO2006/005372 disclosing an electro-pneumatic demandregulator.

However, aviation regulation often requires that at least one crewmemberof an airplane wears permanently a breathing mask when the airplanecruises above a predetermined altitude so that, in case of an abruptdepressurization of the cabin, the crewmember can continue to controlthe airplane.

But the conventional on-demand breathing mask generates an inhalationresistance and, therefore, an increased work of breathing which resultsin fatigue and discomfort. This problem becomes more acute when thebreathing mask must be worn permanently for many hours.

Another problem is related to the oxygen consumption generated by thepermanent use of the breathing mask.

To solve, at least partially, these problems, the applicant hasdisclosed in the patent application having the filing numberQT/EP2006/004586 a breathing mask of the above type in which anauxiliary channel is used to connect the face seal of the breathing maskto the ambient air so that there is no sufficient reduction of pressureinside the breathing mask to cause the regulator to dispense oxygen. Ameans is supplied to regulate flow through the auxiliary channel. Theregulating means has a closed position in which flow is blocked and anopen position in which flow is enabled. A biasing force is applied tothe flow regulating means to maintain it in the closed position. Theuser may manually move the flow regulating means into the open positionwhere a latch is deployed to maintain the flow regulating means in theopen position. The latch may subsequently be released by the user whendesired to revert the flow regulating means to the closed position. Apressure sensing means releases automatically the latch upon decrease inthe cabin pressure, allowing the flow regulating means to revert to theclosed position without action of the user upon such a decrease in cabinpressure.

However, such auxiliary channel has the inconvenience to modifysubstantially the breathing mask and to increase its complexity.

SUMMARY OF THE INVENTION

It would be advantageous to achieve a breathing mask with reduced oxygenconsumption which has some simple mechanisms to be easy to manufactureand to maintain.

To better address one or more concerns, in a first aspect of theinvention a breathing mask for aircraft crewmember comprising anon-demand regulator, said regulator comprising an inlet connected to asource of breathing gas and an outlet to exhaust the breathing gas, saidoutlet having an aperture controlled by a movable valve having an openposition when the crewmember breathes out and a closed position when thecrewmember breathes in, wherein said breathing mask comprises latchmeans operable by said crewmember to latch said valve in the openposition, said latch means comprising an unlocking means to release saidvalve when the cabin pressure is below a predetermined value.

Advantageously, the breathing mask uses a valve already existing inon-demand regulator to add the function of air opening during normalmode of flight. Therefore, the breathing mask has a reduced complexitywhich increases the mask reliability and reduces its cost.

A second advantage of the integration in the on-demand regulator of alatch means to maintain the valve in the open position is the capabilityto link the release of the latch means and a change in another mode ofthe regulator, for instance, the so-called “100% mode” in which the userbreathes in pure oxygen or the “emergency” mode in which the user mustnot inhale the cabin air and therefore the mask cavity is overpressurized compared to the cabin pressure. Therefore, there is no riskthat the mask is set up in two simultaneous non compatible modes.

In particular embodiments:

-   -   said unlocking means comprises an aneroid capsule that changes        in length in response to change in the cabin pressure, said        length change actuating a linkage to release said valve,    -   said latch means comprises a first lever having a position in        which said lever latches said valve in the open position, said        first lever being moved to said position by a button actuated by        the crewmember and said first lever being locked in said        position by second lever actuated by a spring,    -   said second lever is rotating around an axis, the spring and the        aneroid capsule (48) being on each side of the lever to generate        opposing forces,    -   said latch means comprises an electromagnet and said valve        comprises a magnetic part such that the electromagnet maintains        said valve in the open position by a magnetic field,    -   said electromagnet is powered by an electrical circuit and said        unlocking means comprises an aneroid capsule adapted to open        said electrical circuit when the cabin pressure is below a        predetermined value,    -   said electromagnet is movable by the crew member from a first        position far from the valve to a second position near the valve,    -   the electromagnet is hold in the first position by a spring,    -   said latch means comprises a magnet and said valve comprises a        magnetic part such that the electromagnet maintains said valve        in the open position by a magnetic field,    -   said unlocking means comprises an aneroid capsule adapted to        push away the magnetic part from the magnet when the cabin        pressure is below a predetermined value,    -   said latch means comprises a support wheel with flexible        fingers, said fingers having a distal end movable between a        first position in which said movable valve is free to move and a        second position which maintains said movable valve in open        position; and said latch means further comprises a rotating        ratchet acting as a cam to transform the rotary movement of the        ratchet to a translation movement of the fingers between the        first and second position,    -   the unlocking means are automatically activated when the crew        member selects another use mode of the regulator.

Therefore, the breathing mask has the advantage of being easilycalibrated through the spring strength. Another advantage is afford bythe integration of the locking means within the regulator: the manualselector of use mode can be connected to the latch means. Therefore,when the user selects another mode, this “oxygen-saving” mode isautomatically disabled. Depending on the type of on-demand regulator, aparticular embodiment may be preferred as easier to adapt. Aspects ofthese particular embodiments may be combined or modified as appropriateor desired, however.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiment described hereafter inrelation with annexed figures where:

FIG. 1 is a perspective view of a breathing mask known in the art;

FIG. 2 is a schematic view of a part of an on-demand regulator of theprior art;

FIG. 3 is a functional view of a latching mechanism according to anembodiment of the invention;

FIG. 4 is a schematic view of another embodiment of the invention;

FIGS. 5, 6 and 7 are schematic views of a third embodiment of theinvention;

FIG. 8 is a sectional view of a fourth embodiment of the invention; and

FIG. 9 is an isometric view of the embodiment of FIG. 8.

In reference to FIG. 1, a breathing mask 1 comprises a glass 2 fixed toa rigid portion 3. The rigid portion has a form adapted to be fitagainst the face of a user and comprises an on-demand regulator 4 tobring a breathable gas to the user. The breathing mask comprises also anextensible harness 5 having end portions 6 connected to the rigidportion.

The on-demand regulator 4 will not be described in details here exceptfor the parts directly related to the described embodiment of theinvention. If necessary, the above applications contain a completedescription of an on-demand regulator.

In reference to FIG. 2, a portion 10 housing of the regulator isconnected to the face seal 3 defining a chamber 12 surrounding the noseand mouth of the crewmember. The chamber 12 is connected to a source ofbreathing gas through an inlet 14. The on-demand regulator 4 controlsthe flow of breathing gas and its ratio of oxygen content through amechanism not represented but well known in the art.

The portion 10 also defines a breathe-out path 16, or outlet, includingan exhalation or breathe-out valve 18. The shutter element of the valve18 shown is of a type that is in widespread use at present forperforming the two functions of acting both as a valve for pilotingadmission and as an exhaust valve. In the embodiment shown, it actssolely as a breathe-out valve while making it possible for the inside ofthe mask to be maintained at a pressure that is higher than the pressureof the surrounding atmosphere by increasing the pressure that exists ina chamber 20 defined by the valve 18 to a pressure higher than ambientpressure. The valve 18 moves between an open position and a closedposition, depending on the difference of pressure between the chamber 20and the mask chamber 12.

In a first state, an electrically-controlled valve 22 (specifically asolenoid valve) connects the chamber 20 to the atmosphere, in which casebreathing occurs as soon as the pressure in the mask exceeds ambientpressure. In a second state, the valve 22 connects the chamber 20 to theoxygen feed via a flow rate-limiting constriction 24. Under suchcircumstances, the pressure inside the chamber 20 takes up a value whichis determined by a relief valve 26 having a rate closure spring.

In reference to FIG. 3, a rotating lever 30 is linked to the breathe-outvalve 18. The arm of the lever 30 is guided by a pin 32 movable alongits axis. A first end of the pin 32 slides into a fixed part 34 to guidethe pin 32 in its longitudinal movement. The pin 32 comprises a firstcollar 36. A spring 38 is disposed between the fixed part 34 and thecollar 36. A button 40 with a ramp 41 holds the second end of the pin32.

A second lever 42 is rotating around an axis 44. On one side of theaxis, a spring 46 pushes the lever along a second collar 44 of the pin32. On the other side of the axis, the lever arm is controlled by ananeroid capsule 48.

When the user decides to put the breathing mask in a cruise mode inwhich he breathes the ambient air, without consumption of oxygen, hepushes the button 40 until the ramp 41 pushes down the pin 32. If thebutton 40 is of rotating type, the ramp 41 acts as a cam on the pin 32.The lever 42 pushed by the spring 46 latches the pin 32 in the downposition. The movement of the pin 32 rotates the lever 30 until aposition where the valve 18 is maintained in the open position.

As the valve 18 is always open, the mask chamber 12 is always connectedto the cabin ambient air and, therefore, there is no pressure decreaseto open the oxygen inlet and the user breathes an air with lessresistance and which has the same characteristics than the cabin air interm of oxygen percentage, pressure, etc.

The button 40 goes back to its initial position when the user releasesit but the pin 32 is maintained in the down position by the lever 42.

When the breathing mask is in the cruise mode and there is adepressurization of the cabin, the length of the aneroid capsule 48increases due to the pressure decrease. This length increase pushes thelever 42 until it unlocks the pin 32 which returns to its initialposition, moving the lever 30 to release the valve 18 so that theon-demand regulator starts to regulate the oxygen arrival.

The man skilled in the art understands that the spring 46 and theaneroid capsule 48 creates two opposite forces and, therefore, thespring strength must be chosen to push the lever to the latch positionwhen the cabin pressure is above a predetermined level but to be lessthan the aneroid chamber strength when the cabin pressure decreasesunder the predetermined level.

It is particularly advantageous to use the spring 46 to calibrate themechanism to the particularity of the aneroid capsule and thepredetermined pressure as required by aviation regulations.

The level 42 is also manually operable to unlock the pin 32 through abutton (not represented). This release button is advantageously attachedto the control button of the regulator so that, when the user chooses adifferent mode than the cruise mode, the level 42 automatically releasesthe pin 32 and the valve 18 is unlocked and returns to its normal modefor use.

While the invention has been illustrated and described in details in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and not restrictive; theinvention is not limited to the disclosed embodiment.

For instance, the button 40 may be a rotary button or other actuationmechanism.

In another embodiment, FIG. 4, the mechanism to hold the valve 18 in theopen position is based on an electromagnet 50. The electrical currentfor the electromagnet is derived, for instance, from a microphonedisposed in the breathing mask to allow the crewmember to speak with theother crewmembers and people of the air flight control, or from aspecific electrical connection to the plane power supply.

The electromagnet 50 slides into a fixed part 54 and is hold apart fromthe valve 18 by a spring 56. The valve 18 contains a magnetic part 58such as an iron-made pin. To start the cruise mode, the user pushes theelectromagnet 50 toward the valve 18 by means of a button 60. As thevalve 18 contains a magnetic part 58, when the electromagnet is near thevalve 18, the valve 18 is stuck to the electromagnet by the magneticfield. As the user releases the button 60, the electromagnet returns toits initial position and maintains the valve 16 in the open position. Torelease the valve 16, the pressure sensing means 52, for instance ananeroid capsule, or the user, through a switch 64, needs only tosuppress the magnetic field by opening the electric circuit 62.

In another embodiment, the electromagnet may be replaced by a magnetmade of some magnetized material. Such an embodiment is disclosed inreference to FIGS. 5, 6 and 7. In normal mode, FIG. 5, the breathe-outvalve 18 comprises a stem 70 with a magnetic area 72 on its oppositeside. A spring 74, between the valve 18 and a fixed part 76, iscalibrated to maintain the valve in its normal mode, i.e. to allow thevalve to open when the user breathes out. A magnetic box 78 slides inthe fixed part 76 and is pushed away of the magnetic area 72 by a secondspring 80. The magnetic box 78 contains an aneroid capsule 82 with asmall stem 84 to go out of the magnetic box through a hole 86 when theaneroid chamber increases its size due to pressure decrease. A lever 88is maintained in an inactive position by a third spring 90.

To put the regulator in cruise mode, FIG. 6, the user pushes themagnetic box 78 until the magnetic area 72 sticks to it. Then, the userreleases the magnetic box which returns to its initial position with thepressure exercised by the spring 80, bringing with it the valve 18 whichis maintained in open position.

If the cabin pressure decreases below a predetermined level, FIG. 7, theaneroid capsule 82 size increases which pushes out the small stem 84 andthe magnetic area 72 is unstuck from the magnetic box 78. The spring 74pushes the valve 18 to its normal position.

If the user wants to return to the normal mode from the cruise mode, hepushes the lever 88 to unstick the magnetic area 72 from the magneticbox 78.

In FIGS. 8 and 9, the breathe-out valve 18 is shown in the same positionthan in FIG. 2 in relation with a fourth embodiment.

Around the same axis than the valve 18, a flexible support wheel 100 hasa circular shape with 6 fingers 102.

At the distal end of each finger 102 from the wheel center, asemi-spherical area 104 contacts the valve 18 with reduced friction.

On each finger 102, a rigid transmission piece 106 connects the distalend with the external surface of a ratchet 108 so, when the wheel of theratchet turns around the common axis of the valve 18 and of the flexiblesupport 18, the transmission piece 106 slides along the external surfaceof a teeth from a position near the axis to a position away of the axis.As each finger 102 is flexible but not elastic, this movement generatesa vertical and upwards movement of the distal end of the finger and,therefore, the valve 18 is pushed up by the area 104.

The ratchet 108 is rotated through a pin 110 which pushes an arm 112rigidly connected to the wheel 108 and is brought back to its initialposition by a return spring (not represented).

A pawl 114 maintains the ratchet in the pushed position.

A lever 116 rotating around an axis 118 may be pushed by a pin pusher120 or an aneroid capsule 122 to release the pawl 114 so that theratchet 108 returns to its initial position.

Therefore, when the user wishes to put the regulator in the “zero-flow”or cruise mode, he pushes the button 110. The ratchet 108 acting as acam transforms its rotational movement to a vertical movement of thedistal ends of the fingers 102 pushing the valve 18 to an always openposition.

The mechanism is maintained in this position by the pawl 114.

To release the system to its initial position, the user pushes the pinpusher 120 directly or, more preferably, through a manual selector (notrepresented) of the regulator use mode. The pin pusher 120 releases thepawl 114 through the lever 116.

Therefore, when the user selects the “emergency” mode or the “100%”mode, the pawl 114 is automatically released and the valve returns toits normal position.

The same lever is used to release the system when the cabin pressure isbelow a predetermined level through the aneroid capsule 122.

In a particular embodiment, the button 110 is attached to the arm 112 sothat its other end may be used as a tactile indicator of the mode of theregulator.

Other variations to the disclosed embodiments can be understood andeffected by those skilled on the art in practicing the claimedinvention, from a study of the drawings, the disclosure and the appendedclaims. In the claims, the word “comprising” does not exclude otherelements and the indefinite article “a” or “an” does not exclude aplurality.

1. A breathing mask for aircraft crewmember comprising an on-demand regulator, said regulator comprising an inlet connected to a source of breathing gas and an outlet to exhaust the breathing gas, said outlet having an aperture controlled by a movable valve having an open position when the crewmember breathes out and a closed position when the crewmember breathes in, wherein said breathing mask comprises latch means operable by said crewmember to latch said valve in the open position, said latch means comprising an unlocking means to release said valve when the cabin pressure is below a predetermined value.
 2. The breathing mask according to claim 1, wherein said unlocking means comprises an aneroid capsule that changes in length in response to change in the cabin pressure, said length change actuating a linkage to release said valve.
 3. The breathing mask according to claim 2, wherein said latch means comprises a first lever having a position in which said lever latches said valve in the open position, said first lever being moved to said position by a button actuated by the crewmember and said first lever being locked in said position by second lever actuated by a spring.
 4. The breathing mask according to claim 3, wherein said second lever is rotating around an axis, the spring and the aneroid capsule being on each side of the lever to generate opposing forces.
 5. The breathing mask according to claim 1, wherein said latch means comprises an electromagnet and said valve comprises a magnetic part such that the electromagnet maintains said valve in the open position by a magnetic field.
 6. The breathing mask according to claim 5, wherein said electromagnet is powered by an electrical circuit and said unlocking means comprises an aneroid capsule adapted to open said electrical circuit when the cabin pressure is below a predetermined value.
 7. The breathing mask according to claim 5, wherein said electromagnet is movable by the crew member from a first position far from the valve to a second position near the valve.
 8. The breathing mask according to claim 7, wherein the electromagnet is hold in the first position by a spring.
 9. The breathing mask according to claim 1, wherein said latch means comprises a magnet and said valve comprises a magnetic part such that the electromagnet maintains said valve in the open position by a magnetic field.
 10. The breathing mask according to claim 9, wherein said unlocking means comprises an aneroid capsule adapted to push away the magnetic part from the magnet when the cabin pressure is below a predetermined value.
 11. The breathing mask according to claim 1, wherein said latch means comprises a support wheel with flexible fingers, said fingers having a distal end movable between a first position in which said movable valve is free to move and a second position which maintains said movable valve in open position; and said latch means further comprises a rotating ratchet acting as a cam to transform the rotary movement of the ratchet to a translation movement of the fingers between the first and second position.
 12. The breathing mask according to claim 1, wherein the unlocking means are automatically activated when the crew member selects another use mode of the regulator. 